Inappropriate implantable cardioverter-defibrillator shocks in repaired tetralogy of fallot patients: Prevalence and electrophysiological mechanisms

L Goldenthal I, Rosenbaum MS, Lewis M, Sciacca RR, Garan H, Biviano AB.Int J Cardiol Heart Vasc. 2020 May 26;28:100543. doi: 10.1016/j.ijcha.2020.100543. eCollection 2020 Jun.PMID: 32490149 Free PMC article.



Background: Patients with Tetralogy of Fallot (TOF) are at increased risk for sudden cardiac death, often undergo implantable cardioverter defibrillator (ICD) implantation at younger ages, and are at greater risk of experiencing inappropriate shocks. We investigated occurrences of ICD shocks in TOF patients to identify prevalence, characteristics associated with inappropriate shocks, and therapeutic interventions after inappropriate shocks.

Methods: Records of patients with repaired TOF and ICD implantation who were followed at Columbia University Irving Medical Center between 1/1/2000 and 5/1/2019 were analyzed.

Results: 44 patients with repaired TOF and ICD implantation were reviewed. Mean age at implantation was 39 ± 13 years. Eight (18%) patients received both appropriate and inappropriate shocks, 6 (14%) received only appropriate shocks, and 3 (7%) received only inappropriate shocks. Three patients received inappropriate shocks for sinus tachycardia, 7 for atrial arrhythmias, and 1 for noise artifact. Inappropriately shocked patients had lower beat per minute (bpm) cutoff values for ICD therapy (mean = 162 ± 24 bpm vs. 182 ± 16 bpm, p = 0.007). After inappropriate shocks, 1 patient underwent lead replacement, 1 had the VT cutoff increased, and 6 were treated with medications.

Conclusions: One quarter of TOF patients with ICDs experienced inappropriate shock therapy, the timing of which was most often clustered within the first two years after implant or years later. Lower shock therapy zones were associated with increased risk for inappropriate shocks, and the majority of inappropriate shocks resulted from atrial arrhythmias with rapid ventricular response. Treatments for inappropriate shocks included increasing VT therapy bpm and rhythm and/or rate control medications.


Fig. 1 (A) Age at first ICD implant. (B) VT therapy rate at time of shock for patients who experienced shocks, or lowest recorded rate for patients who did not experience shocks. Patients who experienced inappropriate shocks were more likely to have lower VT detection rates than those who did not experience inappropriate shocks.


Fig. 2 (A) Time from most recent prior generator change to first inappropriate or appropriate ICD shock. Inappropriate shocks tended to occur early or late in device lifespan. (B) Time from first ICD implant to first appropriate or inappropriate shock, or until end of follow-up.